1. Field of the Invention
The invention relates to a vehicle surroundings monitoring apparatus and a vehicle surroundings monitoring method.
2. Description of Related Art
There is known an existing image generating device that generates a synthetic image on the basis of images captured by a plurality of cameras mounted on a vehicle and that shows the synthetic image on a display in a vehicle cabin (for example, see Japanese Patent Application Publication No. 2010-274813 (JP 2010-274813 A)). With the configuration described in JP 2010-274813 A, a display image that includes a synthetic image as viewed from a virtual eyepoint is shown on the display. The virtual eyepoint is set at an arbitrary eyepoint location around the vehicle so as to be oriented in an arbitrary viewing direction.
In addition, there is known a technique for showing an image, captured from a host vehicle, on a rear-view mirror (for example, see Japanese Patent Application Publication No. 63-274286 (JP 63-274286 A)).
However, with the configuration described in JP 2010-274813 A, a synthetic image to be shown on the display is generated by using images captured at present by the cameras mounted on the host vehicle at a current location of the host vehicle, so it is difficult to obtain a synthetic image that is able to widely show an area behind the host vehicle. That is, a synthetic image is generated on the basis of images captured at present by the cameras located at a current location of the host vehicle, so the amount of information about an area behind the vehicle is poor.
On the other hand, when an image of a camera (back camera) oriented rearward of the vehicle is used, it is possible to increase the amount of information about an area behind the vehicle. However, when such a rear-view image is directly shown, the direction of flow of an environment in the display image is opposite to the direction of flow of an environment ahead of the host vehicle, directly visually recognized by a driver through a front windshield. Therefore, it is difficult for the driver to instantaneously intuitively understand a surrounding situation mainly an area behind the vehicle. In addition, it is difficult for the angle of view of a camera oriented rearward of the vehicle to acquire information about the vision of the side, oblique rear, or the like, of the vehicle. In addition, when a synthetic image as viewed from a virtual eyepoint oriented forward from a location rearward of the vehicle is generated by using an image captured by a rearward-oriented camera by applying the technique described in JP 2010-274813 A, it is predicted that the synthetic image becomes unrecognizable (unnatural) due to a distortion, or the like, of an image as a result of eyepoint conversion or a range of usage of a rear-view image needs to be reduced eventually.